Efficient method for reusing scale factors to improve the efficiency of an audio encoder

Abstract

An audio encoding system that accepts an audio signal as an input to the system. The system includes a filter bank that splits the audio signal into a plurality of frames, and a bit allocation unit that assigns a number of bits for a current frame of the plurality of frames. The system further includes a scale factor unit that calculates a scale factor, identifies a block type of a first block of a current frame, identifies a block type of a second block consecutive to the first block, and reuses a scale factor of the first block for the second block, when the block type of the first block and the block type of the second block match. The system additionally includes a quantization and coding unit that quantizes and codes the signal, and a bit rate checker that verifies whether a bit rate requirement is satisfied.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority under 35 USC § 119 from Indian Patent Application No. 2495 / CHE / 2007, filed Nov. 2, 2007, the entire contents of which are incorporated herein by reference.BACKGROUND [0002]1. Technical Field[0003]Some embodiments of the present invention relate to the field of audio signal processing. More particularly, an exemplary embodiment relates to improving the efficiency of an audio encoder.[0004]2. Description of the Related Art[0005]Audio processing refers to the processing of sound represented in the form of analog or digital signals. Analog signals are continuous electrical signals, in which a voltage level or a current level represents a sound. In digital signals, a sound wave is represented by binary symbols, i.e., in the form of 1s or 0s. Sound signals are continuous signals, so they must be converted to digital signals by quantizing and sampling the signals. Digital signals offer advantages s...

AI Technical Summary

Benefits of technology

[0017]There is a need for an efficient coding method, which is suitable for any audio encoder, that utilizes iteration loops for encoding methods like MP3 and AAC and that reduces the computing power required for the process of audio encoding. An exemplary embodiment does away with the noise loop and hence, by reducing the processing required for quantization, increases a speed of the audio encoder.

[0018]An object of an exemplary embodiment is to optimize an audio encoder. This method makes use of the fact that an audio signal does not change in its signal characteristics within a very short span of time. This property is utilized to reduce the computation required for a calculation of scale factors. The same method can be applied to a psychoacoustic model and a PNS (Perceptual Noise Substitution) decision to optimize the encoder. The method is very generic and can be adapted for use with any audio encoder.

Problems solved by technology

If the quantization noise is above the limit, then there will be audible noise.

For each block, a scale factor has to be recalculated, resulting in high memory consumption during the process.

This coding method is suitable only for Advanced Audio Coding (AAC) and is not suitable for MPEG 1 Audio Layer 3 (MP3).

Images